JAMB Mathematics Past Questions & Answers - Page 412

2,056.

Solve the equations
m2 + n2 = 29
m + n = 7

A.

(2, 3) and ( 3, 5)

B.

(2, 5) and (5, 2)

C.

(5, 2) and ( 5, 3)

D.

(5, 3) and (3, 5)

Correct answer is B

m2 + n2 = 29 .......(1)
m + n = 7 ............(2)

From (2),
m = 7 - n
but m2 + n2 = 29, substituting;
(7-n)2 + n2 = 29
49 - 14n + n2 + n2 = 29
=> 2n2 -14n + 20 = 0
Thus n2 -7n + 10 = 0

Factorizing;
(n-5)(n-2) = 0
n - 5 = 0, => n = 5
n - 2 = 0, => n = 2.

When n = 5,
m + n = 7, => m = 2,

When n = 2,
m + n = 7, => m = 5.

Thus (m,n) = (5,2) and (2,5)

2,057.

Find the integral values of x and y satisfying the inequality 3y + 5x \(\leq\) 15, given that y > 0, y < 3 and x > 0.

A.

(1,1), (1,2), (1,3)

B.

(1,1), (2,1), (1,3)

C.

(1,1), (3,1), (2,2)

D.

(1,1), (1,2), (2,1)

Correct answer is D

Hint: Sketch the inequality graph for the 3 conditions given and read out your points from the co-ordinates.

2,058.

If two graphs y = px\(^2\) + q and y = 2x\(^2\) -1 intersect at x = 2, find the value of p in terms q.

A.

\(\frac{q-8}{7}\)

B.

\(\frac{7-q}{4}\)

C.

\(\frac{8-q}{2}\)

D.

\(\frac{7+q}{8}\)

Correct answer is B

\(y = px^{2} + q ... (i)\)

\(y = 2x^{2} - 1 ... (ii)\)

At x = 2, 

(i): \(y = p(2^{2}) + q = 4p + q\)

(ii): \(y = 2(2^{2}) - 1 = 7\)

\(\therefore \text{The coordinates of the point of intersection = (2, 7)}\)

(i): \(7 = 4p + q \implies p = \frac{7 - q}{4}\)

2,059.

Divide: \(a^{3x} - 26a^{2x} + 156a^{x} - 216\) by \(a^{2x} - 24a^{x} + 108\).

A.

ax - 2

B.

ax + 2

C.

ax - 8

D.

ax - 6

Correct answer is A

\(\frac{a^{3x} - 26a^{2x} + 156a^{x} - 216}{a^{2x} - 24a^{x} + 108}\)

Let \(a^{x} = z\)

\(\therefore = \frac{z^{3} - 26z^{2} + 156z - 216}{z^{2} - 24y + 108} ... (i)\)

Dividing (i) above, we get \(z - 2\)

= \(a^{x} - 2\)

2,060.

Evaluate \(\frac{(0.14^2 \times 0.275)}{7(0.02)}\) to 3 decimal places.

A.

0.039

B.

0.385

C.

0.033

D.

0.038

Correct answer is A

\(\frac{(0.14)^{2} \times 0.275}{7(0.02)} = \frac{(0.14)^{2} \times 0.275}{0.14}\)

= \(0.14 \times 0.275\)

= \(0.0385 \approxeq 0.039\)

Note: Embedded zeroes are counted just the same as non-zero digits and For the number of decimal places stated, count that number of digits to the right of the decimal and underline it.

The next number to its right is called the 'rounder decider'. If the 'rounder decider' is 5 or more, then round the previous digit up by 1